Pinellas, Hillsborough and Pasco Counties begin evacuations today as the first hurricane warnings were issued for parts of southern Florida with the state braced for what could be a catastrophic hit from Hurricane Irma over the weekend.

Pinellas County commissioners ordered a mandatory evacuation of all residents living in coastal areas.

The evacuation order starts at 6 a.m. Friday but residents have until 8 a.m. Sunday to leave.

The evacuation order also includes residents with special needs and those who live in mobile homes in any part of the county.

The order is for anyone who lives in a home in Zone A, which includes all low-lying areas and coastal areas that are vulnerable storm surge.

Pinellas County has opened seven shelters to accommodate an estimated 160,000 residents who will be affected by the order.

Hillsborough County will begin voluntary evacuations at 8 a.m. Friday for residents in Zone A who are registered for special needs shelters, officials said.

Pasco County Government is recommending voluntary evacuation for residents who live west of U.S. 19, special needs residents, anyone who lives in a manufactured home, mobile home, or RV, and anyone who lives in a low-lying area or an area prone to flooding.

At 11 a.m. Friday, Pasco is opening five shelters for residents who would like to leave their home ahead of the storm.

When counties mandate evacuations, they will do it by zones A through E. Hillsborough commissioners said they will decide Friday evening if residents in zones B and C will need to evacuate starting Saturday morning.

Evacuation zones are not the same as FEMA flood zone designations.

You can find a list of shelters for Pinellas, Hillsborough, Pasco and Manatee Counties here.

National Hurricane Center forecasters on Thursday night issued a warning for a sizeable segment of Florida, including the Miami metro area and Lake Okeechobee.

A storm surge warning has also been issued for the same area.

Irma weakened from a Category 5 storm to Category 4 on Friday morning with maximum sustained winds near 155 mph, but it remained a powerful hurricane.

Irma rolled past the Dominican Republic and Haiti on Thursday and spun along the northern coast of Cuba on Friday morning. Thousands of tourists were evacuated from low-lying keys off the Cuban coast Thursday in anticipation of 20-foot storm surges. Buses loaded with tourists began streaming out of Santa Maria, Cayo Coco, Cayo Guillermo and other keys dotted with all-inclusive resorts.

All residents of the area were under mandatory evacuation orders from the Cuban government, which was moving tens of thousands of people from vulnerable coastline.

More than a half-million people in Miami-Dade County were ordered to leave as Irma closed in.

Brian McNoldy, a hurricane researcher at the University of Miami, said Irma could easily prove to be the costliest storm in U.S. history.

"Take it seriously, because this is the real deal," said Maj. Jeremy DeHart, a U.S. Air Force Reserve weather officer who flew through the eye of Irma at 10,000 feet (3,048 meters).

As South Florida fell under hurricane warnings, gas shortages and gridlock plagued thousands of people fleeing for high ground ahead of Irma.

Carmen Pardo and her 6-year-old daughter, Valeria, drove around Miami for seven hours, gas station to gas station, frantically searching for somewhere to fill up the tank to evacuate. They found nothing.

"She was saying, 'Mommy I'm so tired, I can't do this anymore,'" she said Thursday. "It was craziness."

Pardo booked the only flight she could find leaving the city, to Orlando, where she reserved two seats on a bus bound for Tallahassee on Friday.

"It's the beginning of an adventure," she said.

Late Thursday, the National Hurricane Center issued the first hurricane warnings for the Keys and parts of South Florida, including some of the Miami metropolitan area of 6 million people and Lake Okeechobee. It added a storm surge warning and extended watch areas wrapping around the tip of the peninsula.

People along the Atlantic coast anxiously watched the behemoth while Irma battered the northern Caribbean, killing at least 11 people and leaving thousands homeless after destroying buildings and uprooting trees.

At least 31,000 people fled the Florida Keys, which could begin seeing wind and rain from Irma as early as Friday night, Gov. Rick Scott said. He noted the size of the powerful storm, and told residents not to become complacent.

"It is wider than our entire state and could cause major and life-threatening impacts from coast to coast. Regardless of which coast you live on, be prepared to evacuate," Scott said. He ordered all public schools, colleges and universities to close Friday through Monday.

With winds that peaked at 185 mph, Irma has been the most powerful hurricane ever recorded in the Atlantic.

NASA secured Kennedy Space Center and SpaceX launched an unmanned rocket for an experimental flight. Kennedy closed its doors to all nonessential staff and a crew of about 120 people will ride out the storm on site.

Most of the critical buildings at Kennedy are designed to withstand gusts of up to 135 mph (220 kph). Irma's wind could exceed that if it reaches Cape Canaveral.

Georgia Gov. Nathan Deal ordered evacuations for all areas east of Interstate 95, including the city of Savannah, and authorized about 5,000 National Guard members to help with response and recovery. Georgia was last struck by a hurricane of force Category 3 or higher in 1898.

Noel Marsden said he, his girlfriend, her son and their dog left Pembroke Pines north of Miami with plans to ride out Irma in Savannah, only to find the city was also shutting down because of Irma. Marsden wasn't sure where they would all end up.

"I've got a buddy in Atlanta and a buddy in Charlotte. We'll wind up one of those two places because there are not hotels, I can tell you that," he said.

Irma's eventual path and Florida's fate depends on when and how sharp the powerful hurricane takes a right turn, National Weather Service Director Louis Uccellini said.

"It has become more likely that Irma will make landfall in southern Florida as a dangerous major hurricane," the Hurricane Center said in a forecast discussion Thursday afternoon.

The last Category 5 storm to hit Florida was Andrew in 1992. Its winds topped 165 mph, killing 65 people and inflicting $26 billion in damage. It was at the time the most expensive natural disaster in U.S. history.

U.S. Air Force Reserve weather officer Maj. Jeremy DeHart flew through the eye of Irma at 10,000 feet Wednesday and through Hurricane Harvey just before it hit Texas last month.

He said Irma's intensity set it apart from other storms.

"Spectacular is the word that keeps coming to mind. Pictures don't do it justice. Satellite images can't do it justice," DeHart said.

Irma battered the Turks and Caicos Islands early Friday and Cuba evacuated tourists from beachside resorts as the fearsome storm continued a rampage through the Caribbean that has killed at least 11 people.

Waves as high as 20 feet (6 meters) were expected in the Turks and Caicos. Communications went down as the storm slammed into the islands, and the extent of the devastation was unclear.

Following in Irma's wake was Hurricane Jose, with some of the islands hit hardest by Irma in its expected path.

French, British and Dutch military authorities rushed aid to a devastated string of Caribbean islands where at least 11 people were dead and thousands homeless. Warships and planes were sent with food, water and troops after the hurricane smashed homes, schools and roads, laying waste to some of the world's most beautiful and exclusive tourist destinations.

The first islands hit by the storm were scenes of terrible destruction.

French Prime Minister Edouard Philippe said Thursday that four people were confirmed dead and about 50 injured on the French side of St. Martin, an island split between Dutch and French control, where homes were splintered and road signs scattered by the fierce winds. The cafes and clothing shops of the picturesque seaside village of Marigot were submerged in brown floodwaters. The toll could rise because rescue teams had yet to get a complete look at the damage.

Looting was reported in St. Martin. Annick Girardin, minister for France's overseas territories, described on BFM television Friday "scenes of pillaging" of televisions as well as food and water. She lamented "how people can take advantage of the distress of others" and said it's essential for police to restore order and ensure urgent care for victims.

The U.S. Consulate General in Curacao said it believes about 6,000 Americans are stranded on St. Martin. It said it was working with the U.S. and other governments to try to figure out how to get the Americans off the island either by air or boat. Frantic Americans were calling home to relatives to try to get them off the island ahead of Hurricane Jose.

At least four people were killed in the U.S. Virgin Islands, and officials said they expected to find more bodies. Authorities described the damage as catastrophic and said crews were struggling to reopen roads and restore power.

Three more deaths were reported on the British island of Anguilla, as well as Barbuda and the Dutch side of St. Martin.

The hospital on St. Thomas was destroyed and dozens of patients were being evacuated to St. Croix and Puerto Rico by the U.S. Coast Guard. Local official said a U.S. Navy hospital ship was arriving as early as Friday to care for unknown numbers of injured and two Air Force C-130s transport planes were bringing in food and water.

Power lines and towers were toppled, leaves were stripped off plants and trees, a water and sewage treatment plants was heavily damaged and the harbor was in ruins, along with hundreds of homes and dozens of businesses. Gov. Kenneth Mapp imposed a 6 p.m. curfew.

The primary focus for now is "making sure people have meals, water and shelter," Mapp said. "An event of this magnitude is very chilling."

Irma also slammed the French island of St. Barts, tearing off roofs and knocking out electricity in the high-end tourist destination.

French Interior Minister Gerard Collomb said 100,000 food rations were sent to St. Barts and St. Martin, the equivalent of four days of supplies.

"There is no power, no gasoline, no running water. Houses are under water, cars are floating through the streets, inhabitants are sitting in the dark in ruined houses and are cut off from the outside world," he said.

Big waves smashed a dozen homes into rubble in the Dominican fishing community of Nagua, but work crews said all the residents had left before the storm. Officials said 11,200 people in all had evacuated vulnerable areas, while 55,000 soldiers had been deployed to help the cleanup.

In Haiti, two people were injured by a falling tree, a national roadway was blocked by debris and roofs were torn from houses along the northern coast but there were no immediate reports of deaths. Officials warned that could change as Irma continued to lash Haiti, where deforested hillsides are prone to devastating mudslides that have wiped out entire neighborhoods of precariously built homes in flood zones.

"We are vulnerable. We don't have any equipment to help the population," Josue Alusma, mayor of the northern city of Port de Paix, said on Radio Zenith FM.

French President Emmanuel Macron's office said he would go to the islands as soon as the weather permits it.

On Barbuda, nearly every building was damaged when the hurricane's core crossed almost directly over the island early Wednesday. About 60 percent of its roughly 1,400 residents were left homeless, Antigua and Barbuda Prime Minister Gaston Browne said.

Hundreds of miles to the west, Florida prepared for Irma's wrath, with forecasters warning the storm could slam headlong into the Miami metropolitan area of 6 million people, punish the entire length of the state's Atlantic coast and move into Georgia and South Carolina.

Farther out in the Atlantic, Hurricane Jose, a Category 3 storm with 125 mph (200 kph) winds, posed a potential threat for Saturday to some of the same islands ravaged by Irma.

Irma, the most potent Atlantic Ocean hurricane ever recorded, appeared increasingly likely to rip into heavily populated South Florida on Sunday afternoon after sweeping along Cuba's northern coast on Saturday.

Hurricane Irma lashed Puerto Rico with heavy rain and powerful winds Wednesday night, leaving nearly 900,000 people without power as authorities struggled to get aid to small Caribbean islands already devastated by the historic storm.

Florida rushed to prepare for a possible direct hit on the Miami area by the Category 5 storm with potentially catastrophic 185 mph winds.